Motor vehicle crashes are the major cause of death and injury among adolescents. PRB has developed a program of research, including observational and prospective studies, designed to increase understanding of teen driving risks and reduce crash risks during the early months of licensure. Results from our initial studies indicated that teen risky driving behaviors, traffic violations, and crashes were related to low parental monitoring and lenient driving restrictions, especially during the first month of licensure. Based on these findings, the Checkpoints Program was developed to increase parental management of teen unrestricted driving through the use persuasive communications (PCs) in the forms of newsletters and a model driving agreement. Versions of the Checkpoints Program are currently being tested in several large, randomized trials. The results of our research thus far show promise for increasing parent limits on teen driving. In Connecticut, 4,950 parent-teen dyads were recruited as teens obtained learner's permits. Families were randomly assigned to intervention or comparison groups. Intervention families receive the Checkpoints video, newsletters, and driving agreement during the mandatory four-month permit period and follow-up newsletters for the first six months of licensure. Intervention effects are assessed at licensure, and three, six and twelve months post-licensure. Preliminary results from the first 450 parent-teen dyads indicate that both parents and teens in the intervention group report stricter limits on teens' driving at night, with teen passengers, and on high-speed roads at licensure and three-months post-licensure than do those in the comparison group. By 12 months post-licensure, parental restrictions had declined in both groups, but remained significantly higher in the intervention group. In Maryland, 658 parent-teen dyads were recruited as teens obtained provisional driver?s licenses. Families were randomly assigned to intervention or control groups by week of recruitment. Intervention families watched the Checkpoints video and received the Checkpoints Parent-Teen Driving Agreement at the Motor Vehicle Administration. Intervention effects are assessed at one, four, and nine months post-licensure. Preliminary results indicate that compared to parents and teens in the control group, both parents and teens in the intervention group reported stricter limits on teens' driving and higher use of a driving agreement at one and four months post-licensure. By 12 months post-licensure, parental restrictions had declined in both groups but remained significantly higher in the intervention group. Current studies are designed to evaluate methods for increasing the effectiveness of parent interventions. Other studies are underway to examine the nature of teen driving risks, including the evaluation of the effects of supervised practice driving, driving experience, teen passengers, and the use of electronic devices on driving performance.